Hola Kiko,
Si funciona, tenés que correr el siguiente script en la base.
CREATE OR REPLACE FUNCTION pg_catalog.varchartoint(character varying) RETURNS integer
STRICT IMMUTABLE LANGUAGE SQL AS 'SELECT
int4($1::text);';
CREATE CAST (character varying AS integer) WITH FUNCTION
pg_catalog.varchartoint(character varying) AS IMPLICIT;
Saludos ,
Eugenia